EPIC is a seven country European cohort study designed to further investigate associations between diet, hormones, xenobiotics, and cancer. The study will also enable analyses of risk factors for other chronic diseases. It is planned to enroll 400,000 subjects, with about equal number of men and women. A number of pilot studies have already evaluated dietary questions that have been prepared independently in the different countries. In addition, serum and urinary biochemical markers of dietary variables have been collected. The British cohort of the EPIC study includes 25,000 men and women to be recruited from Cambridgeshire and Norfolk and also another 50,000 subjects to be chosen from across the country. The 25,000 subjects close to Cambridge University will be enroll ed over four years. A questionnaire containing medical history, dietary and other lifestyle information will be completed and returned by mail. A research nurse will perform a simple examination and obtain blood and urine specimens. Finally, one week diet diary will be completed and repeated after four years. Cancer endpoints will be found using the nationwide cancer registry, and deaths by linkage with death certificate files. At Oxford, a unique contribution to the EPIC Study is the planned enrollment of 30,000 vegetarian subjects. These subjects will be partly found from the existing Oxford cohort of vegetarians and partly through vegetarian societies and subscribers to vegetarian magazines. Otherwise their data will be collected as described above. In addition, the existence of the established Oxford cohort of vegetarians and a similar Welsh cohort, provide a unique collaborative opportunity, whereby with the California data, the largest amount of data ever assembled from vegetarians and vegan vegetarians have differing health experiences.